The API documentation is missing from CS6.
There is no link in CS6 help and the only things I can find by searching are the CS5 documentation.
Anyone from Adobe (or close to) know when this will be finished and uploaded??
According to the Fireworks Help page, Adobe will be releasing Help PDFs for CS6 in June.
I suspect the Extending Fireworks CS5 version would be fairly complete. Except for new features, the documentation and API seem to be quite static.